I think the fact that the Genesis (sedan) challenges the luxury brands it's a matter of perception too. I sat in one, the V6 model, and it felt like a very well done mainstream vehicle, but nowhere near the feel of a BMW, Audi or Lexus. Not even Acura or Volvo.
I guess the fake plastic wood, the grain on the dash and door panels - same as on the lower end vehicles, the big, four-spoke steering wheel with the similar design as any other Hyundai had a major contribution. Sure, it comes with a lot of features standard, but the luxury features don’t make a luxury vehicle.
The exterior looked nice though and very well executed.